1. Technical Field
The present invention relates to an image photographing device, and more particularly, to an image photographing device capable of being miniaturized to have a simple structure by improving a damping structure, reducing a impact amount of a lens barrel, reducing generation of noise due to impact, and preventing generation of pre-pressure at the time of driving the lens barrel to reduce power consumption.
2. Description of the Related Art
Recently, use of a subminiature camera for a mobile has been gradually increased in a mobile device such as a mobile phone, a notebook, a tablet PC, or the like. The demand of customers for the subminiature camera used in the mobile device and having a high pixel of five million pixels or more and a multi-function such as a zoom function, an auto focus (AF) function, and the like has been increased.
Generally, a camera module used in the mobile device may be configured to include an optical system having a lens, a lens driver moving the optical system in an optical axis direction to adjust a focus, and an image sensor photographing light input through the optical system to convert the photographed light into an image signal.
The camera module configured as described above moves an optical system, that is, a lens barrel including at least one lens along with the optical axis direction through the lens driver such as an actuator in order to auto-focus the optical system on the image sensor
In the case of the image photographing device such as the camera module according to the related art, in order to prevent noise of the lens barrel due to external impact, a protruding portion is formed on a housing of the actuator surrounding the lens barrel to limit a movement of the lens barrel in the optical axis direction as shown in FIG. 1, and an elastic member is interposed on an upper side of the lens barrel to provide pre-pressure to the lens barrel as shown in FIG. 2.
However, in the case of an image photographing device 10 shown in FIG. 1, since a lens barrel 11 is supported in a housing, that is, a member fixed at the time of driving the lens barrel 11, by an elastic member 13, elastic force of the elastic member 13 acts as pre-pressure in a direction opposite to a movement direction of the lens barrel 11 along with an optical axis. Therefore, since driving force for driving the lens barrel 11 cannot but increase, power consumption increases. In addition, when the elastic member 13 is deformed, the elastic force of the elastic member 13 is changed at the time of driving the lens barrel 11, such that it is difficult to linearly drive the lens barrel 11, thereby deteriorating capacity and reliability.
In addition, in the case of an image photographing device 20 shown in FIG. 2, as elastic force of an elastic member 23, that is, a compression coil spring, interposed on an upper side of a lens barrel 21 acts as pre-pressure force, such that power consumption increases at the time of driving the lens barrel 21 in an optical axis direction. In addition, when excessive external impact occurs, the elastic member 23 is permanently deformed, such that it is difficult to linearly drive the lens barrel 11, thereby deteriorating capacity and reliability.
In addition, in accordance with the recent trend toward an increase in pixel and miniaturization of an image photographing device such as a camera module, it is important to move a lens barrel in an optical axis direction without a tilt, such that a rolling support scheme by a ball, a driving support scheme by a shaft, or the like, instead of a scheme of supporting the lens barrel by an elastic member has been applied. In this case, only generation of a tilt with respect to movement of the lens barrel in the optical axis direction may be prevented, and a damage and noise are generated due to impact between the lens barrel and other structures at the time of applying external impact or external power to the lens barrel.